When roads and the like are submerged in water during heavy rains or floods, the water also enters buildings, parking lots, and the like that are located therearound and causes further damage. In this case, if a means to prevent the entry of water is provided in passages leading to the buildings, the parking lots, and the like, the damage can be reduced. Based on this viewpoint, there is a water blocking board apparatus which is arranged in passages and can prevent entry of a given amount or more of water.
Heretofore, various types of water blocking board apparatuses have been suggested, and a water blocking board apparatus as disclosed in Patent Document 1 for example is one of them. The water blocking board apparatus (flood preventing apparatus) described in Patent Document 1 has: a water collecting bucket which is disposed inside a water collecting pit being a groove dug from a road surface; and a water blocking board (flood preventing board) in a board shape which is arranged in an accommodating pit being a groove dug from another part on the road surface and is capable of projecting from and retracting into the accommodating pit. The water collecting bucket and the water blocking board are configured to pull each other by means of a lifting chain and a sprocket. At normal times, the water blocking board is accommodated in the accommodating pit and balanced in a position that an upper end of the water blocking board is in line with the road surface. On the other hand, in a case of flooding or the like, water accumulates in the water collecting bucket and the water collecting bucket descends due to the weight of the water; then, the water blocking board ascends in a manner being pulled up. The water blocking board ascends and thereby projects from the road surface so as to block part of the passage, and prevents further entry of water.